Problem with new entry lock

Entry lock wouldn't unlock from outside with key. Bought a similar entry lock and had it keyed to work with old lock's keys. Installed it and the interior knob is very stiff to lock. My wife, who isn't muscular but not feeble by any means, can't turn it to lock. I can but it takes a lot of pressure. It unlocks quite easily from inside. Locks and unlocks readily with key from outside. Is there a way to free this up or do I need to take it back to lock shop where I bought it. (That entails most of a day's travel to town and back.)

Thanks oh'Mike. I'll start with the easy parts first. My location is Lummi Island, WA. The lock is a General Lock and the style is Tylo.
I think I'm with you on the adjustable set back except I don't know what the correct position is. It is almost flush with the door edge. Perhaps 1/16 inch further out than the door edge.
I haven't disassembled the lock yet to see if it is centered. I'm not sure what it is supposed to be centered on. I see, however, that the plate that the screws go through is maybe 1/16 closer to the door edge than were the plates that I removed when I took the old lock out. Is that what you are telling me to check? That the latch mechanism needs to be pushed back into the door a bit further? If so, how do I do that? Tap the whole thing a bit further into the hole cut in the door?

Take the knob off on both sides....leave the latch in place and take your same picture #1 looking straight through the hole.

That's what he meant by centered (I think anyway, Mike correct me if I'm wrong). The hole in the latch where the spindle goes through should be in the center of the larger hole on the face of the door. If it's not, it puts the spindle in a bind.

It uploaded. Wish I knew a bit about operating computers and fixing things. I'll give it one more try. However, I got everything back together and, while it doesn't twist easily as the old lock did, my wife can now lock and unlock the door so I must have improved some alignment enough that we can get in and out without climbing through a window. Thanks for the help guys.
Jerry

Knob turns fine and turning the thumb knob to unlock was okay but turning the knob to lock took a lot of pressure to turn. I could turn it (and I'm 79 but moderately strong yet) but my young bride, who is about 5' 2" and weighs like a feather, could not lock the door. Living on a little island where everyone knows everyone really makes door locks unnecessary but she grew up in the big city (50,000 people!) and she believes someone will do a home invasion. Of course, the whole front door is glass so a lock is really just something to make her feel safer. Anyhow, thanks again for all the good advice.
Jerry